Eucalyptus Fiber Morphology and Inter Fibre Hydrogen Bond Density
Eucalyptus fiber collapse and hydrogen bond density dictate sheet tensile strength, bulk retention, and landed sheet cost in commercial packaging grades.
Cationic Starch Bridging
Chemical Mechanism
Flocculation of cellulose fibres during papermaking depends on the attraction between charged polymers and the negatively charged surfaces of the pulp. In this wet-end process, cationic starch bridging occurs when high molecular weight starch chains adsorb onto multiple fibres or fine particles simultaneously, forming physical links across the gap between them. This electrostatic and physical connection increases first-pass retention of fillers on the forming wire.
By building these macromolecular networks, the process captures mineral fillers that would otherwise escape through the forming fabric into the white water system.
Retention Consequence
Papermakers adjust the dosage of modified potato or corn starches to optimize the drainage rate on the forming fabric without compromising sheet formation. Excess starch can lead to charge reversal and subsequent steric stabilization, which decreases retention instead of improving it.
Strength Correlation
The resulting paper structure displays enhanced dry strength due to the increased internal bonding of the consolidated fibre network. Mechanical properties like the Scott bond value and tensile index increase as more hydrogen bonds are established via the starch molecules. In high-recycled-content boards, these polymeric additions are essential to compensate for the shortened fibres and the higher contaminant loads that typically impede sheet cohesion.